Time - Man of the Year/Time_Man_of_the_Year_Compact_Publishing_3YX-Disc-1_Compact_Publishing_1993.iso/moy/061592/0615300.000

Text File | 1992-09-22 | 8KB | 167 lines

                                                                                SCIENCE, Page 60

What's Wrong with the Weather?


There's nothing unusual about unusual weather. But global
warming, a volcano and a stray ocean current may be making things
even freakier.

By PHILIP ELMER-DEWITT -- Reported by David Bjerklie/New York,
with other bureaus


    Just when summer should have been coming in, it snowed
last week in Colorado, punctuating several days of unseasonable
32 degrees C (90 degrees F) weather with enough snowfall to
close three mountain highways. Paris was hit with a torrential
rainstorm -- the worst in a decade -- that crippled the city,
poisoned the Seine with sewer effluent, and clogged the river
with 300 tons of dead fish. In one hour in early May, a squall
dumped a record 110 mm (4 1/3 in.) of rain on Hong Kong, turning
steep city streets into rushing rivers and killing five. In the
Middle East this January, the wettest, coldest winter in recent
memory was capped by a storm that blanketed Amman, Damascus and
Jerusalem with much more snow than anyone there had seen for 40
years.

    If it continues as it has begun, 1992 could turn out to be
almost as bizarre as 1991, a year in which North America's
spring arrived in winter, its summer in spring and its winter
in autumn. The period from December 1991 to March 1992 has
already gone into the National Weather Service's record books
as the warmest winter in at least 97 years. It hardly rained at
all in rainy Seattle in May. Texas in January was swamped with
twice as much precipitation as normal, and Southern California,
where it never rains, was socked with floodwaters so powerful
they carried cars out to sea. Africa is having its worst drought
in 50 years, and eastern Australia, which is supposed to have
summer when the northern hemisphere has winter, had to do
without this year. Instead of balmy days and bright sunshine,
Melbourne racked up a record 12 consecutive days of rain and the
coldest January in 137 years, which is as far back as anyone
Down Under kept track.

    What is going on? Experts say fluctuations from normal
readings are, well, normal and that weird weather is the rule,
not the exception. But the highs and lows and wets and drys over
the past two years have been so extreme that anxious questions
are arising. Could these outbursts of wacky weather be related
to those fires from the gulf war? That hole in the ozone layer?
The global warming trend that environmentalists have been
predicting for so many years?

    The questions are more than idle speculation. This week at
the Earth Summit in Rio de Janeiro, world leaders will be
adding their signatures to a treaty to prevent climate change,
a document that was significantly weakened during presummit
negotiations, in part because of U.S. contentions that the
threat of global warming has been overblown. But the Bush
Administration's skepticism must contend with the direct
experience of millions of citizens who are worried that when the
weather gets as odd as it has been of late, something must be
wrong.

    Scientists, however, are more cautious than the
umbrella-carrying public. Even climatologists who believe that
global warming may eventually trigger extreme weather variations
like the ones we are experiencing say it is too early to prove
a direct connection. The outbreak of freakish weather could also
have been partly caused by one or more of several large-scale
atmospheric events now under way. The main suspects, in
descending order of likelihood:

    EL NINO. To meteorologists, the weather phenomenon named
after the Christ child is not a theory but a recognizable and
recurrent climatological event. Every few years around
Christmastime, a huge pool of warm seawater in the western
Pacific begins to expand eastward toward Ecuador, nudging the
jet streams off course and disrupting weather patterns across
half the earth's surface. The El Nino that began last year and
is now breaking up has been linked to record flooding in Latin
America, the unseasonably warm winter in North America and the
droughts in Africa.

    PINATUBO. The full effects of the eruption of Mount
Pinatubo in the Philippines last June -- probably the largest
volcanic explosion of the 20th century -- are starting to be
felt this year. The volcano heaved 20 million tons of gas and
ash into the stratosphere, where they formed a global haze that
will scatter sunlight and could lower temperatures -- by half
a degree Fahrenheit -- for the next three or four years. Smoke
from the gulf-war fires, by contrast, never reached the
stratosphere and had no measurable effect on the world's
weather.

    GREENHOUSE GASES. It is known that the level of CO2,
methane and other heat-trapping gases in the atmosphere has
increased 50% since the start of the Industrial Revolution.
Measurements also indicate that the world's average temperature
has increased 1 degree F over the past 100 years. The rest is
conjecture. Computer models suggest that as the buildup of
greenhouse gases continues, average temperatures could jump 3
degrees F to 9 degrees F over the next 60 years. Some scientists
speculate that even a small rise in average temperatures could
lead to greater extremes in weather patterns from time to time
and place to place.


    The problem with sorting out these influences is that they
interact in complex ways and may, to some extent, cancel each
other out. Pinatubo's cooling effects could counteract the
warming caused by greenhouse gases, at least over the short
term. At the same time, El Nino's warming influence seems to
have suppressed the early cooling effects of Pinatubo's global
haze.

    Predicting the weather is, in the best of circumstances,
a game of chance. Even with the most powerful supercomputers,
forecasters will never be able to see ahead more than a couple
of weeks with any accuracy. Climatologist Stephen Schneider of
the National Center for Atmospheric Research compares the
typical weather forecast to guessing what bumpers a pinball will
hit after it has left the flipper. "What's happening now," he
says, "is we're tilting the machine in several directions at
once."

    Of course, there have always been volcanic eruptions, and
the tales of El Nino date back at least to the Spanish
conquistadors. Old-timers can point to freak weather occurrences
that put the Los Angeles floods to shame, like the 1928 storm
that bombarded southwestern Nebraska with hailstones the size
of grapefruit. Or the blizzard of 1888 that buried the Eastern
Seaboard in snowdrifts the size of four-story buildings. "There
is a record set somewhere every day," says Steve Zebiak, an
atmospheric scientist at Columbia University's Lamont-Doherty
Geological Observatory.

    What is new is that for the first time some of the
influences that shape our weather are man-made. Experts say it
could be 20 or 30 years before they know for certain what effect
the buildup of greenhouse gases, the destruction of ancient
forests or the depletion of the ozone layer have had.
Policymakers looking for excuses not to halt those trends will
always be able to point to scientific uncertainty. As Schneider
puts it, "We're insulting the system at a faster rate than we
can understand." The risk is that by the time we understand what
is happening to the weather, it may be too late to do anything
about it.